Antiarthritic β-cycloalkyl-β-oxopropionitriles

ABSTRACT

Disclosed herein are novel β-cycloalkyl-β-oxopropionitriles which exhibit anti-inflammatory/antiarthritic activities.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a β-oxo-propionitriles active asanti-inflammatory and anti-arthritic agents, to their use in thetreatmen of inflammatory or arthritic conditions, and to pharmaceuticalcompositions containing the novel compounds.

2. Description of Related Art

Benzoylacetonitrile (I) and its monofluoro analogues have been found tobe effective inhibitors of adjuvant-induced arthritis in rats (J. Med.Chem., 1979, 22:1385-9). The same article, as well as U.S. Pat.No.4,189,436, also discloses β-oxo-β-thiophenepropionitriles (II) asanti-arthritic agents. ##STR1##

β-Oxopropionitriles having an α-carbonyl or thiocarbonyl substituent arereported as anti-inflammatory and/or anti-arthritic agents in (a)through (e):

(a) U.S. Pat. No. 4,061,767 and German Offenlegungsschrif No. 2,555,789disclose, resectively, 2-hydroxyethylidenecyanoacetic acid anilidederivatives of formulas (IIIa) and (IIIb), wherein Ar is inter aliamono-, di-, or tri-substituted phenyl, said substituent may be, forexample, halogen, alkyl, alkoxy, or halo-substituted alkyl. ##STR2##

(b) U.S. Pat. Nos. 4,254,047, 4,254,048, 4,254,049, 4,170,656, and4,173,650 disclose a group of compounds that may be represented by thegeneric structure (IV) wherein X is oxygen, sulfur, methylene, or adirect bond; Ar is phenyl opt. substituted with one or more of the sameof different groups selected from halogen, alkyl, alkoxy,trifluoromethyl, and trichloromethyl. ##STR3##

(c) U.S. Pat. No. 4,197,310 discloses thiophenepropionitriles of formula(V) wherein R is hydrogen, lower alkyl, or halogen. ##STR4##

(d) U.S. Pat. Nos. 4,256,759, 4,644,010 and 4,435,407 discloseβ-oxo-β-carbamoylpyrrolepropionitriles encompassed by generic formula(VI) where R¹ is H or alkyl; R² and R³ are independently H or alkyl; andR⁴ is phenyl or a heterocyclic radical both of which may be opt.substituted with alkyl, alkoxy, hydroxy, halogen, or trifluoromethyl.##STR5##

(e) German Offenlegungschrift No. 3,217,446 disclosesthiocarbamoyl-thenoylacetonitriles of formula (VII) wherein R¹ is H,halogen, alkyl, or alkoxy; R² is C₃₋₆ cycloalkyl, benzyl, furfuryl, orphenyl opt. substituted with halogen alkyl, alkoxy, alkyllthio, ortribluoromethyl. ##STR6##

(f) British Patent 1,112,210 discloses 2-cyanomalonic acid thioamidederivatives of formula (VIII) wherein R¹ is inter alia alkyl or aralkyl;R² is H, alkyl, or aryl; and R³ is alkyl or aralkyl. ##STR7## Thesecompounds are said to be useful as bactericides, fungicides, anddiuretics. No anti-inflammatory or anti-arthritic acivities aredisclosed.

(g) The preparation of 3-cyanopentane-2,4-dione from cyanogen andacetylacetone was reported in Berichte, 1898, 31:2944; however, nobiological property was disclosed.

Compounds of the present invention may be distinguished over compoundsdisclosed in items (a)-(g) above by the presence of both theβ-cycloalkyl group, and the β-aliphatic substituted carbamoyl group orthe α-alkanoyl group.

A list of additional references disclosing compounds having theα-carbonyl-β-oxopropionitrile fragment is given below; however, thecompounds described therein are not ketonitriles and have not beenreported as anti-inflammatory or anti-arthritic agents.

(h) U.S. Paten 3,406,183 discloses3-N-arylamino-3-mercapo-2-cyano-acrylamides of the formula (IX) whereinR¹ is H and R² is alkyl or phenyl; or R¹ and R² together represent-(CH₂)₄₋₅ -; and Ar is opt. substituted phenyl. ##STR8## These compoundsare alleged to be useful as anhelmintic and antibacterial agents.

(i) Pabst (Arch. Pharm., 1929, 267:325-52) reported the preparation of aseries of 2-cyanomalonamic acid esters and amides, for example, (X) and(XI). ##STR9##

(j) U.S. Pat. No. 3,016,295 discloses 2-cyanomalonamic acid esterderivatives having formula (XII) wherein R² is alkyl or alkyl-(OCH₂ CH₂-)₁₋₂ and R² is H or alkyl. ##STR10## These compounds are said to beuseful in altering growth characteristics of plants.

SUMMARY OF INVENTION

The present invention provides compounds having the formula (XIII)##STR11## wherein

n=2, 3, 4, or 5;

A is selected from the group consisting of C₁₋₅ alkyl, NHR¹, and NR² R³wherein R¹ is selected from the group consisting of C₁₋₅ alkyl, C₂₋₅alkenyl, C₂₋₅ alkynyl, and C₃₋₆ cycloalkyl with the proviso that when nis 2, R¹ is not ethyl or isopropyl; R² and R³ are same or different C₁₋₅alkyl;

or a pharmaceutically acceptable salt thereof.

A preferred embodiment provides compounds of formula (XIII) wherein n is2 or 3, with n=2 being the most preferred.

A further preferred embodiment provides compounds of formula (XIII)wherein A is C₁₋₅ alkyl, di(C₁₋₅ alkyl)amino, or NHR¹ wherein R¹ isselected from the group consisting of methyl, C₄₋₅ alkyl, C₃₋₅ alkenyl,C₃₋₅ alkynyl, or C₃₋₄ cycloalkyl with methyl being the most preferredR¹.

A further aspect of the present invention provides a pharmaceuticalcomposition which comprises an anti-inflammatory or an anti-arthriticeffective amount of a compound of formula (XIII) and a pharmaceuticallyacceptable carrier.

Yet a further aspect of the present invention provides a method fortreating a mammalian host afflicted with an inflammatory or arthriticcondition which comprises administering to said host ananti-inflammatory or anti-arthritic effective amount of a compound offormula (XIII).

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "alkyl" includes straight nd branched carbonchain.

Compounds of the present invention may exist in equilibrium with theenol form (XIIIa); however, for the sake of uniformity and convenience,the compounds are depicted as the keto form throughout thespecification. It will be appreciated that the tautomeric hydrogen issufficiently acidic to form salts with pharmaceutically acceptableinorganic or organic bases such as alkali metal or alkaline earth metalhydroxides; ammonia; mono-, di-, or trialkylamines; heterocyclic amines;or mono-, di-, or ri(hydroxyethyl)amines; these salts are also withinthe scope of this invention. ##STR12##

The α-carbamoyl- or α-alkanoyl-β-oxopropionitriles of the presentinvention may be prepared by methods known in the literature; inparticular by (1) base-catalyzed ring opening of the appropriatelysubstituted isoxazole; or (2) reacting a β-oxopropionitrile with anisocyanate to provide the α-carbamoyl compound, or with an acid halideto provide the corresponding α-alkanoyl derivative.

Scheme 1 shows the reacion steps for the preparaaion ofisoxazole-4-carboxamides and the subsequent ring opening to provide thecorresponding α-carbamoyl-β-oxopropionitrile product. ##STR13## whereinR and R¹ are independently a lower alkyl group; R² is H and R³ isselected from the group consisting of C₁₋₅ alkyl, C₁₋₅ alklenyl, C₂₋₅alkynyl, and C₃₋₆ cycloalkyl; or R² and R³ are same or different C₁₋₅alkyl.

The starting material β-cycloalkyl-β-oxopropionate (prepared by theprocedure described in J. Am. Chem. Soc., 1948, 70:497) is heated withan excess of an trialkyl orthoformate such as riethyl orthoformate in anacid anhydride usch as cetic anhydride, preferably to the refluxingtemperature of the reaction mixture, for several hours. The resultanenol eher is treated with at least an equimolar amount of hydroxylaminein an organic solvent such as ethanol at elevated temperature,preferably refluxing temperature of the reaction mixture, to provide theisoxazole carboxylate. The carboxylate is converted to the amide byconventional method involving the hydrolysis of the ester group underacidic conditions, reacting the resultant carboxylic acid with thionylchloride, and finally treating the acid chloride with the appropriateamine. The amine may serve as the hydrogen chloride acceptor if at leasttwo molar equivalents are used; alternatively, a tertiary amine such asdiisopropylethylamine may be used for that purpose. Treatment of theisoxazole carboxamide with a basic reagent, e.g. sodium hydroxide,sodium methoxide, sodium carbonate, or potassium hydroxide, provides thecorresponding α-carbamoyl-β-cycloalkyl-β-oxopropionitrile. The generalconcept illustrated in Scheme 1 is applicable for the preparation of theα-alkanoyl derivatives by sustituting the starting β-keto ester with a1,3-dione derivative [see for example, Ann. Chim. (Rome), 1965,55:1233-41 (Chem. Abstr. 65:3853e, 1966)].

Scheme 2 shows an alternative procedure for the preparation of compoundsof the present invention. ##STR14## wherein R¹ is the same as definedfor formula (XIII).

Condensation of the ketonitrile with an isocyanate or an acid chloridemay be effected in the presence of at least a molar equivalent, butpreferably aa slight molar excess, of an organic or an inorganic base.Suitable bases may be for example, an organic amine base such astriethylamine, an alkali metal hydroxide, or an alkali metal alkoxide.The reaction is carried out in an organic solvent at ambienttemperature. The starting keonitriles may be prepared by acylation ofacetonitrile by procedures described in Synthesis, 1984, 1-26. Theketonitriles may also be advantageously prepared by the followingprocedure (Scheme 3): a cycloalkanecarboxylic acid is added to a stirredsolution of carbonyldiimidazole in an anhydrous organic solvent such astetrahydrofuran. A solution of cyanoacetic acid in organic solvent istreated with a strong base, e.g. Grignard reagent such as isopropylmagnesium chloride. The mixture is stirred for several hours, and to itis added, dropwise, the previously prepared carbonyl imidazolidesolution. After several hours of stirring, the reaction is quenched byaddition of acid. The solution is extracted with an appropriate organicsolvent such as ethyl acetate or ether, washed, and further purified bychromatography to give pure ketonitrile product. ##STR15##

BIOLOGICAL ACTIVITY

Compounds of the present invention exhibit valuable pharmacologicalproperties, in particular, anti-inflammatory and anti-arthriticactivities. Representative compounds have been tested in the followingin vivo models:

A. Modified Developing Adjuvant Arthritis in Rats

This test is based on the procedure originally described by Pearson(Proc. Soc. Biol. Med., 1956, pp 91-5). Each experimental group used sixmale Lewis rats weighing approx. 250 gm. Arthritis was produced by asingle intradermal injection of Mycobacterium butyricum (0.6 mg in 0.1ml mineral oil) into the base of the tail. Test compounds wereadministered orally, once daily, starting on the day of inoculation(day 1) through day 8. The initial dosage was reduced during this periodwhen side effects were observed. The paw volume (average of two hindpaws) was measured by the merccury displacement method at least twiceweekly during the course of the experiment (40 to 42 days). The efficacyof a compound was expressed as the percent reduction of hind paw volumeof treated vs. untreated rats using the following equation: ##EQU1##

B. Carrageenin Induced Paw Edema in the Rat

This test is based on the procedure originally described by Holsappleand Yim (Inflammation, 1984, 8:223). Six male Sprague Dawley ratsweighing approx. 300 gm were used in each experimental group. The ratshad been starved for 24 hours prior to injection of 0.1 ml of 1%carrageenin into the plantar surface of the left hind paw. Testcompounds were dosed orally 30 minutes prior to carrageeninadministration. The volumes of the left hind paws were measured bymercury displacement at 2,4, and 6 hours following carrageenininjection. The efficacy of a compound was expressed as the percentinhibition of carrageenin injected paw volume as compared tonon-injected paw using the following equation: ##EQU2## The peak of drugeffects usually occurred 2-4 hours following carrageenin injection.

C. Delayed Type Hypersensitivity (DTH)

Male Lewis rats were immunized on Day 1. Mycobacterium butyricum inmineral oil (6 mg/ml) was injected into the base of the tail at 0.1 mlper rat. A negative control group receiving an equal amount of mineraloil was included. Drug therapy was administered orally from day one today eight. Delayed type hypersensitivity was tested on day 9. Purifiedprotein derivative (Tuberculin PPD, Statens Seruminstitute, TuberculinDepartment, DK-2300 Copenhagen S, Denmark) was dissolved in phosphatebuffered saline at 2.5 mg/ml. Twenty μl (50 μg) of the PPD solution wasinjected intradermally into the right ear of the rat, and theconralateral ear received 20 μl of the phosphate buffered salinevehicle. Forty-eight hours after injection the thickness of both earswas measured to the nearest 0.01 mm using a hand held caliper. Thedifference between the thickness of right and left ears was defined asthe delta value for each rat. Group means and standard errors werecompared using a Dunnett's 2-tail test.

Table I contains results of both modified developing adjuvant arthritisand carrageenin induced paw edema models.

                                      TABLE I                                     __________________________________________________________________________    Activities in adjuvant-induced polyarthritis (AIP)                            and carragenin-induced paw edema (CIP) models                                  ##STR16##                                                                                  AIP                                                             Compound              Inhib. score.sup.b                                      Ex. #                                                                             n = 2     Dose (mg/kg).sup.a                                                                    d. 20-22                                                                           d. 40-42                                                                           CIP.sup.c                                     __________________________________________________________________________    5   ACH.sub.3 95 (d. 1-2)                                                                           ++   ++   I                                                           50 (d. 3-8)                                                     1   NHCH.sub.3                                                                              100     ++++ ++++ I                                             2   NHC(CH.sub.3).sub.3                                                                     100                                                                              (d. 1-2)                                                                           ++   +++  I                                                           50 (d. 3-8)                                                     8   NHCH.sub.2 CHCH.sub.2                                                                   100                                                                              (d. 1-4)                                                                           0    0    A                                                           50 (d. 5-8)                                                     4   NHCH.sub.2 CCH                                                                          50      +++  ++ + A                                                  ##STR17##                                                                              100                                                                              (d. 1-3)                                                                           +    ++   I                                                           50 (d. 4)                                                       6                                                                                  ##STR18##                                                                              100     +    +    I                                             3   N(CH.sub.3).sub.2                                                                       100     +++  +++  I                                                 n = 3                                                                     7   ANHCH.sub.3                                                                             100     0    +    I                                             __________________________________________________________________________     .sup.a once daily, p.o., from d. 1-8 (unless otherwise specified).            .sup.b % Inhibition of paw edema: 0 = <25; + = 25- <40; ++ = 40-<60; +++      60-<80; ++++ = 80-100.                                                        .sup.c test compound administered as a single oral dose of 50 mg/kg 30        min. prior to carrageenin injection. % Inhibition determined 4 hrs. after     carragenin injection; I = <25% reduction in paw volume and A = ≧25     reduction in paw volume.                                                 

Table II shows the effect of compound of Example 1 on the DTH responseto Mycobacterium butyricum challenge in rats.

                  TABLE II                                                        ______________________________________                                        Effect of drug on delayed-type hypersensitivity (DTH) response                          Dose                                                                Compound of                                                                             mg/kg/d × 8 d.p.o.                                                                     % Reduction-DTH                                      ______________________________________                                        Example 1 60             56                                                             30             41                                                             10             20                                                   ______________________________________                                    

Compounds of the present invention show anti-inflammatory and/oranti-aarthritic activities in the animal models used. In addition,compound of Example 1 exhibits immunomodulating activity as evidenced byits ability to reduce delayed hypersensitivity in arthritic rats.

Compounds of the present invention may be formulated into pharmaceuticaldosage forms suitable for administration via convenient routes such asoral, intravenous, intramuscular, subcutaneous, topical andintra-aricular. The formulated dosage forms may contain, in addition tothe active agent, other pharmaceutically acceptable excipients to impartdesirable pharmaceutical properties, for example, increased stability,improved taste, and improved appearance.

Compositions intended for oral administration may be in the form oftablets, pills, hard or soft gelaatin capsules, powders, elixirs,syrups, and suspensions. Tablets pills, powders and the like may containadditionally: a binder such as starch, gelatin, methylcellulose, ortragacanth; a disintegraant such as potato starch, alginic acid, oragar; a lubricant such as magnesium stearate, or polyethylene glycol; adiluent such as lactose, dextrose, mannitol, or cellulose; and/or otherinert ingredients such as absorbants, colorants, flavoring agents, orsweeteners. Injectable compositions are preferably solutions orsuspensions in a vehicle such as water, a pharmaceutically acceptablenon-aqueous solvent, or a mixture thereof. They may contain, in additionto the active compound, preservatives (suchc as phenylmercuric nitrate,benzalkonum chloride, thimerosal, and benzyl alcohol), anaioxidants(such as sodium bisulfite and acetone sodium bisulfite), emulsifiers, orbuffers (such as citrates, acetates and phosphates). For intravenousadministration, the unit dosage form may be diluted with conventional IVfluids such as sterile Water for Injection, NaC1 Solution, or Ringer'sSolution.

It will be appreciated that the actual preferred dosage of the compoundsof the present invention will vary according to the particular compoundbeing used, the particular formulation, mode of administration, and theseverity of the disease being treated. Characteristics of the afflictedhost such as sex, age, body weight, liver function, kidney function, andother concurrent drug therapies may also be considered by the attendignclinician. Optimal dosages for a given set of conditions can beascertained by those skilled in the art using conventional dosagedetermination tests in view of the experimental animal data provided.

The following examples are illustrative of the present invention and arenot to be construed as limiting its scope.

EXAMPLE 1 ##STR19## β-Cyclopropyl-β-oxo-α-methylcarbamoylpropionitrileA. β-Cyclopropyl-β-oxopropionitrile

Cyclopropanecarboxylic acid (13.63 g, 0.15 mole) was added at 15° C. toa stirred solution of carbonyldiimidazole (24.36 g, 0.15 mole) in 300 mlof dry THF and the mixture waas stirred at ambient temperature for 2 h.

A solution of cyanoacetic acid (26.79 g, 0.315 mole) in 240 ml ofmethylene chloride plus 500 ml of dry THF was treated dropwise over 90min with 315 ml of isopropylmagnesium chloride (2.0 M solution in THF)while maintaining the reaction temperature at <15° C. The white mixturewas stirred at 23 ° C. for 2 h and to it was added, dropwise, thecarbonyl imidazolide solution prepared above. Stirring was continued atroom temperature for 17 h.

The reaction mixture was chilled in an ice bath and quenched by thecautious addition of 500 ml of 3 N HCl. The organic layer was removed atreduced pressure and the residue was extracted with several portions ofeither. The extracts were washed once with water, dried and evaporatedto give a dark viscous liquid containing cyanoacetic acid. Distillationof the oil gave the ketonitrile as a near colorless liquid stillcontaminated with some cyanoacetic acid; bp 117°-139° C. (17 mm). Flashcchromatography of the crude product on silica agel using methylenechloride-Skellysolve B (85:15) as the eluant provided pure titlecompound that was distilled once again to a colorless oil. Yield: 12.20g (75%); bp 124°-128° C. (21 mm).

Anal. Calcd for C₆ H₇ NO : C, 66.04; H, 6.46; N, 12.83. Found: C, 65.60:H, 6.65; N, 12.77.

B. β-Cyclopropyl-β-oxo-α-mehylcarbamoylpropionitrile

A solution of β-cyclopropyl-β-oxopropionitrile (3.50 g, 32.1 mmoles)[prepared in Step A]and triethylamine (TEA) (3.57 g, 35.3 mmoles) in 40ml of toluene was treated at 20° C. with methyl isoccyanate (1.92 g,33.7 mmoles) and the resultant solution was stirred at room temperataurefor 17 h. The solvent was evaporated a reduced pressure and the syrupyresidue, dissolved in 10 ml of methanol, was poured into a cold, stirredmixture of 100 ml water plus 5 ml 6 N HCl. The precipitate was collectedby filtration and recrystallized from 90% aqueous ethanol to yield 4.18g of the title compound, mp 130°-133° C.

Anal. Calcd for C₈ H₁₀ N₂ O₂ : C, 57.82; H, 6.06; N, 16.86. Found: C,57.66; H, 6.08; N, 16.90.

EXAMPLE 2 ##STR20##α-tert-Butylcaarbamoyl-β-cyclopropyl-β-oxopropionitrile A. Ethylβ-cyclopropyl-α-ethoxymethylene-β-ketopropionate

Ethyl β-cyclopropyl-α-ketopropionate (247.0 g, 1.58 mole) [preparedaccording to the procedure described in J. Am. Chem. Soc., 70 , 497(1948)], triethyl orthoformate (468.3 g, 3.16 mole) and acetic anhydride(484.0 g, 4.74 mole) were combined and the solution was stirred atreflux for 4 h and at ambient temperature for 17 h. The excess reagentswere distilled at water aspirator pressure (maximum head temperaturepermitted was 72° C.) and the oily pot residue was stirred at 10° C.with a mixture of ether and water. The ether layer was separated, washedonce with cold water and dried over Na₂ SO₄. Removal of the solvent gave321.5 g (96%) of an orange-red liquid that was used directly in the nextstep.

B. Ethyl 5-cyclopropylisoxazole-4-carboxylate

A mixture of hydroxylamine hydrochloride (105.0 g. 1.51 mole), ethylβ-cyclopropyl-α-ethoxymethylene-β-ketopropionate (320.0 g., 1.51 mole)[prepared in Step A], and 1200 ml of ethanol was refluxed for 2 h. Thesolvent was removed in vacuo and the residue was partitioned betweenwater and ether. The organic phase was separated, washed again withwater, dried and evaporated to leave a dark, greasy solid. Triturationof the crude product under Skellysolve B gave 158 g of the titlecompound.

A second crop of ester (50.0 g) was obtained by chromatographing thedark filtrate on 300 g of silica gel using first ca. 1 L of SkellysolveB-ether (95:5) followed by 3 L of Skellysolve B-ether (9:1). Total yield76%. An analytical sample was prepared by recrystallizing an aliquotfrom a warm mixture of 10:1 Skellysolve B/ether, mp 52°-55° C.

Anal. Calcd for C₉ H₁₁ NO₃ : C, 59.66; H, 6.12; N, 7.73. Found: C,59.72; H, 6.24; N, 7.62.

C. 5-Cyclopropylisoxazole-4-carboxylic acid

Ethyl 5-cyclopropylisoxazole-4-carboxylate (203.0 g, 1.12 mole)[prepared in Step B]was added to a solution of 405 ml of glacial aceticacid plus 505 ml of 6 N HCl and the mixture was heated in an oil bath a105°-110° C. for 3 h. After 18 h at ambient temperature the thickmixture was diluted with water, cooled in an ice bath and filtered togive 140.8 g of the title acid. Recrystallization of an aliquot fromacetonitrile gave an analytical sample, mp 163°-165° C.

Anal Calcd for C₇ H₇ NO₃ : C, 54.90; H, 4.60; N, 9.14. Found: C, 54.73;H, 4.51; N, 9.16.

D. 5-Cyclopropylisoxazole-4-carbonyl chloride

Thionyl chloride (195.8 g, 1.65 mole) was added dropwise to a stirredmixture of 5-cyclopropylisoxazole-4-carboxylic acid (140 g, 0.914 mole)[prepared above in Step C] and Na₂ CO₃ (106.0 g, 1.0 mole) in 650 ml ofchloroform. The mixture was heated at gentle reflux for 4 hr, then thesolid was filtered and the filtrate evaporated to an oil. Distillationyielded 134.8 g of the acid chloride as a colorless liquid that readilycrystallized to a low melting solid, bp 123°-125° C. (13 mm).

Anal. Calcd for C₇ H₆ C1NO₂ : C, 49.00; 4, 3.52; N, 8.16. Found: C,49.67; H, 3.80; N, 8.06.

E. 5-Cyclopropylisoxazole-4-(N-er-butyl)carboxamide

A solution of tert-butylamine (7.25 g, 99 mmoles) in 25 ml of methylenechloride was added dropwise at 10° C. to a solution of5-cyclopropylisoxazole-4-carbonyl chloride (8.50 g, 49.5 mmoles)[prepared in Step D]in 100 ml of methylelne chloride and the reactionmixture was stirred at ambient temperature for 1 h. The mixture was thenwashed twice with water (6 HCl was added if necessary to make the washesacidic), dried and evaporated. The residual solid was recrystallizedfrom Skellysolve B-ethyl acetate (4:1) to yield 6.71 g of the titlecompound as a white solid, mp 116°-118.5° C.

Anal. Calcd for C₁₁ H₁₆ N₂ O₂ : C, 63.44; H, 7.75; N, 13.45. Found: C,63.28; H, 7.81; N, 13.45.

F. α-tert-Butylcarbamoyl-β-cyclopropyl-β-oxopropioonitrile

Sodium hydroxide (33 ml of a 1.0 N solution) was added at 10° C. to asuspension of 5-cyclopropylisoxazole-4-(N-tert-butyl)carboxamide (6.83g, 32.8 mmoles) [prepared in Step E]in 35 ml of water plus 5 ml ofmethanol and the mixture was stirred at room temperature until solutionwas complete. The cooled solution was then acidified with 6 N HCl andthe precipitate was filtered. Recrystallization from 20% aqueous ethanolgave the title compound (5.23 g) as a white solid, mp 97°-98.5° C.

Anal. Calcd for C₁₁ H₁₆ N₂ O₂ : C, 63.44; H, 7.75; N, 13.45. Found: C,63.58; H, 8.01; N, 13.48.

EXAMPLE 3 ##STR21## β-Cyclopropyl-α-dimethylcarbamoyl-β-oxopropionitrileA. 5-Cyclopropylisoxazole-4-(N,N-dimethyl)carboxamide

A solution of 5-cyclopropylisoxazole-4-carbonyl chloride (8.0 g, 46.6mmoles) [prepared in Example 2, Step D]in 80 ml of methylene chloridewas reacted with a solution of dimethylamine (4.96 g, 0.11 mole) in 44.6ml of methylene chloride according to the general procedure of Example2, Step E. Distillation of an aliquot of the crude product gave thetitle compound as a colorless oil, bp 114°-116° C. (0.03 mm).

Anal. Calcd for C₉ H₁₂ N₂ O₂ : C, 59.98; H, 6.71; N, 15.55. Found: C,60.09; H, 7.02; N, 15.46.

B. β-Cyclopropyl-α-dimethylcarbamoyl-β-oxpropionitrile

The product from Step A above (4.0 g, 22.2 mmoles) in a mixture of 40 mlof water plus 5 ml of methanol was treated at 10° C. with 23 ml of 1.0 Nsodium hydroxide and the mixture was stirred at room temperature for 90min. The resulting solution was cooled, acidified with 6 N HCl and theprecipitate filtered. Recrystallization from 45% aqueous ethanol yielded3.08 g of the title compound, mp 44.5°-46° C.

Anal. Calcd for C₉ H₁₂ N₂ Ohd 2 : C,59.98; H, 6.71; N, 15.55. Found: C,59.88; H, 6.93; N, 15.60.

EXAMPLE 4 ##STR22##β-Cyclopropyl-β-oxo-α-propargylcarbamoylpropionitrile A.5-Cyclopropylisoxazole-4-N-(propargyl)carboxamide

The general procedure of Example 1, Step E was repeated, except that thetert-butylamine utilized therein was replaced with two equivalents of2-propynylamine. The crude product was placed on 65 g of silica gel andchromatographed using first methylene chloride followed by methylenechloridemethanol (98:2). This yielded 76% of the title compound that wasrecrystallized from ethyl acetate/Skellysolve B, mp 83°-85.5° C.

Anal. Calcd for C₁₀ H₁₀ N₂ O₂ : C, 63.14; H, 5.30; N, 14.73. Found: C,63.42; H, 5.39; N, 14.86.

B. β-Cyclopropyl-β-oxo-α-propargylcarbamoylpropionitrile

A suspension of 5-cyclopropyl-4-N-(2-propynyl)-carboxamide (2.12 g, 11.1mmoles)[prepared in Step A]in 15 ml of water plus 5 ml of methanol wastreated at 10° C. with 12.5 ml of 1.0 N NaOH and he mixture was stirredat ambient temperature until solution was observed. The solution wasthen cooled, acidified with 6 N HCl and the product collected byfiltration. Recrystallization from 40% aqueous acetonitrile gave thetitle compound (1.72 g) as a white solid, m.p. 127.5°-129° C.

Anal. Calcd for C₁₀ H₁₀ N₂ O₂ : C, 63.14; H, 5.30; N, 14.73. Found: C,62.79; H, 5.37; N, 14.80.

EXAMPLE 5 ##STR23## α-Acetyl-β-cyclopropyl-β-oxopropionitrile

n-Buyllithium (19.44 ml, 52.5 mmole of a 2.7 M solution in hexane) wasadded at -15° C. to a solution of diisopropylalmine (5.31g, 52.5 mmole)in 80 ml of dry THF. After 10 min the cooling bath was lowered to -70°C. and 5-methylisoxazole (4.15 g, 50 mmoles) was added to the lithiumdiidopropylalmine (LDA) solution followed in 30 min by the dropwiseaddition of cyclopropanecarboxylic acid chloride (5.33 g, 50 mmoles) in15 ml of THF. The reaction mixture was then stirred at -78° C. for 30min and at ambient temperature for 2 h. The solvents were evaporated andthe residue was partitioned between ether, 30 ml of water and 13 ml of 4N NaOH. The aqueous layer was separated, acidified with 6 N HCl andextracted with two portions of ether. The extracts were dried andevaporated to a slushy solid that was cchromatographed on 100 g ofsilica gel using methylene chloride-Skellysolve B (95:5). Theappropriate fractions were combined and concentrated to yield 2.26 g ofthe title compound as a yellow-tinted solid, mp 62°-63.5° C.

Anal. Calcd for C₈ H₉ NO₂ :C, 63.57; H, 6.00; N, 9.27. Found: C, 63.48;H, 6.01; N, 9.13.

EXAMPLE 6 ##STR24##α-Cyclobutylcarbamoyl-β-cyclopropyl-β-oxopropionitrile A.5-Cyclopropylisoxazole-4-(N-cyclobutyl)carboxamide

The general procedure of Example 2, Step E was repeated, except that thetert-butylamine utilized therein was replaced with one equivalent eachof cyclobutylamine and diisopropylethylamine. The crude oil was placedon 70 g of silica gel and chromatographed using methylene chloridefollowed by methylene chloride containing 2% methanol. The appropriatefractions were combined and evaporated to give a waxy solid.Recrystallization from ethyl acetate/Skellysolve B yielded 39% of thetitle compound, mp 103°-105° C.

Anal. calcd for C₁₁ H₁₄ N₂ O₂ : C,64.06; H, 6.84; N, 13.59. Found: C,64.17; H, 7.01; N, 13.57.

B. α-Cyclobutylcarbamoyl-β-cyclopropyl-β-oxopropionitrile

A suspension of 5-cyclopropylisoxazole-4-(N-cyclobutyl)carboxamide (3.10g, 15 mmoles) [prepared in Step A]in 15 ml of water plus 5 ml ofmethanol was treated at 0° C. with 16 ml of 1.0 N NaOH and the mixturewas stirred at ambient temperature until solution was observed. Thesolution was then cooled, acidified with 6 N HCl and he productcollected by filtration. Recrystallization from 30% aqueous ethanolyielded 1.86 g of the title compound as a white solid, mp 110°-111° C.

Anal. Calcd for C₁₁ H₁₄ N₂ O₂ : C,64.06; H, 6.84; N, 13.59. Found: C,63.68; H, 7.04; N, 13.43.

EXAMPLE 7 ##STR25## β-Cyclobutyl-β-oxo-α-methylcarbamoylpropionitrile A.β-Cyclobutyl-β-oxopropionitrile

The general procedure of Example 1, Step A was repeated, except thatathe cyclopropanecarboxylic acid utilized therein was replaced with anequivalent amount of cyclobutanecarboxylic acid. After workup,purification by chromatography on silica gel and distillation, the titlecompound was obtained as a yellow-tinted liquid, bp 118°-121° C. (11mm).

Anal. Calcd for C₇ H₉ NO : C, 68.27; H, 7.37; N, 11.37. Found: C, 68.02;H, 7.63; N, 11.12.

B. β-Cyclobutyl-β-oxo-α-methylcarbamoylpropionitrile

β-Cyclobutyl-β-oxopropionitrile (2.25 g, 18.3 mmoles) [prepared in StepA]was reacted with methyl isocyanate (1.10 g, 19.2 mmoles) according tothe general procedure of Example 1, Step B to yield 2.57 g of the titlecompound as a white solid afater recrysstallization from 50% aqueousethanol, mp 81°-83° C.

Anal. Calcd for C₉ H₁₂ N₂ O₂ : C, 59.98; H, 6.71; N, 15.55. Found: C,60.17; H. 6.71; N. 15.52.

EXAMPLE 8 ##STR26## α-Allylcarbamoyl-β-cyclopropyl-β-oxopropionitrile

When β-cyclopropyl-β-oxopropionitrile (2,.00 g, 18.3 mmoles) [preparedin Example 1, Step A]was reacted with allylisocyanate (1.60 g, 19.2mmoles) according to the general procedure of Example 1, Sep B, thetitle compound (2.8 g) was obtained as a white solid afterrecrystallization from 30% aqueous ethanol, m.p. 72°-73.5° C.

Anal. Calcd for C₁₀ H₁₂ N₂ O₂ : C, 62.48; H, 6.29, N, 14.58. Found: C,62.70; H, 6.32; N, 14.60.

EXAMPLE 9 ##STR27##α-Cyclopropylcarbamoyl-β-cyclopropyl-β-oxopropionitrile A.5-Cyclopropylisoxazole-4-(N-cyclopropyl)carboxamide

The general procedure of Example 2, Step E was repeated, except that twoequivalents of tert-butylamine utilized therein were replaced with oneequivalent of cyclopropylamine and one equivalent ofdiisopropylethylalmine. The crude product was purified by flashchromatography using methylene chloride followed by methylenechloride-methanol (98:2) and then recrystallized from ethylacetate-Skellysolve B to yield 76% of the title compound, mp 102°-105°C.

Anal. Calc. for C₁₀ H₁₂ N₂ O₂ : C, 62.48; H, 6.29; N, 14.58. Found: C,62.19; H, 6.36; N, 14.55.

B. α-Cyclopropylcarbamoyl-β-cyclopropyl-β-oxopropionitrile

The general procedure described in Example 6, Step B was followed except5-cyclopropyylisoxazole-4-(N-cyclopropyl) carboxamide was used in placeof the N-cyclobutyl analog used therein to provide the title compound asa white solid, m.p. 136°-138.5° C.

EXAMPLE 10

The general procedure described in Example 2, Step E was repeated excepttert-butylamine used therein was replaced by methlamine to provide5-cyclopropylisoxazole-4-(N-methyl)-carboxamide, m.p. 77°-80° C. heisoxazole thus obtained may be subjected to treatment with NaOH usingthe procedue of Example 2, Step F to provide the product of Example 1.

What is claimed is:
 1. A compound having the formula ##STR28## whereinn=2, 3, 4, or 5;A is C₁₋₅ alkyl, NHR¹, or NR² R₃ ; wherein R¹ isselected from the group consisting of C₁₋₅ alkyl, C₂₋₅ alkenyl, C₂₋₅alkynyl, and C₃₋₆ cycloalkyl with the proviso that when n is 2, R¹ isnot ethyl or isopropyl; and R² and R³ are the same or different C₁₋₅alkyl;or a pharmaceutically acceptable salt thereof.
 2. The compound ofclaim 1 wherein A is C₁₋₅ alkyl.
 3. The compound of claim 2 wherein n is2 and A is methyl.
 4. The comound of claim 1 wherein A is NHR¹.
 5. Thecompound of claim 4 wherein n is
 2. 6. The compound of claim 5 whereinR¹ is selected from the group consisting of methyl, C₄₋₅ alkyl, C₃₋₅alkenyl, C₃₋₅ alkynyl, and C₃₋₄ cycloalkyl.
 7. The compound of claim 6wherein R¹ is methyl.
 8. The compound of claim 6 wherein R¹ istert-butyl.
 9. The compound of claim 6 wherein R¹ is propargyl.
 10. Thecompound of claim 6 wherein R¹ is allyl.
 11. The compound of claim 6wherein R¹ is cyclobutyl.
 12. The compound of claim 6 wherein R¹ iscyclopropyl.
 13. The compound of claim 4 wherein n is 3, 4, or
 5. 14.The compound of claim 13 wherein n is 3 and R¹ is methyl.
 15. Thecompound of claim 1 wherein A is NR² R³.
 16. The compound of claim 16wherein R² and R³ are each methyl and n is
 2. 17. A pharmaceuticalcomposition comprising a therapeutically-effective amount of a compoundof claim 1 and a pharmaceutically acceptable carrier.
 18. A method fortreating a mammalian host suffering from arthritic condition whichcomprises administering to said host an anti-arthritic effective dose ofa compound of claim
 1. 19. A method for treating a mammalian hostsuffering from inflammation condition which comprises administering tosaid host an anti-inflammatory effective dose of a compound of claim 1.